Introduction
According to my comment from question I finally found some time to deal with this problem myself. After reading many articles, and auditing many other site's code I ve partial answer. Most of them are theoretically deduced from given sources. I will update this answer after full implementation of social content on my site which will happen in the next few days.
Anserw
Q: Is there any solution to implement og meta tags without creating an app and implementing the Login Plugin (without losing performance)?
A: This is possible. But owner lose some analytics from insight programm.
Quotes from link: https://developers.facebook.com/docs/plugins/checklist/, https://developers.facebook.com/docs/opengraph/creating-object-types/.
fb:app_id
The unique ID that lets Facebook know the identity of your
site. This is crucial for Facebook Insights to work properly.
og:type
The object type for this object - to see what the type is for your og:type, go to the Open Graph section of the App Dashboard, click on Types, choose your object type and check the Open Graph Type field under the Advanced section. Note that once an object's type is set and has been used in a story that its type can not be changed. For a list of built-in types, please see our list of common open graph object types.
After registering website as app in facebook we may toggle insight analytics for this. Otherwise we can not get data about likes/shares etc. from domain strictly. But this is only advantage of this kind solution which I encountered.
For tag type we may use predefined objects list https://developers.facebook.com/docs/reference/opengraph/object-type in result it can be also implemented without app.
Q: If I have to fulfill those two steps, is it possible to implement the Login Plugin without allowing users to log into the site with it?
A: Yes it is.
After this step we may integrate our website like facebook app and insight analytics also but it wont give any profits if we wont allow users to log in site with it. https://developers.facebook.com/docs/insights/:
App Insights
To build the best possible experience for people using your app, use
Insights to track how its being used. For app administrators, Insights
includes feedback for stream stories, referral traffic to your app, a
breakdown of the actions that contribute to active user count,
demographics on authorized users and active users and the number of
times permissions are prompted and granted. Detailed Insights on Open
Graph activity for your app are also available. In addition, Insights
provides diagnostics for your app so you can track API errors as well
as get access to allocations and throttling information.
People who have not granted permissions to your app are not considered
active users, but they're counted in other metrics such as impression
data.
This data will be build from people who 'liked' your app/page - it wont give any viable statistics if noone can reach it.
Live Examples
My link:
https://www.facebook.com/plugins/like.php?action=like&show_faces=false&share=true&domain=kwejk.pl&href=http://kwejk.pl/obrazek/1952891/&node_type=link
Original link:
https://www.facebook.com/plugins/like.php?action=like&api_key=565589606823878&channel_url=http%3A%2F%2Fstatic.ak.facebook.com%2Fconnect%2Fxd_arbiter.php%3Fversion%3D28%23cb%3Df2a3883e08%26domain%3Dkwejk.pl%26origin%3Dhttp%253A%252F%252Fkwejk.pl%252Ff3423111e%26relation%3Dparent.parent&colorscheme=light&extended_social_context=false&font=arial&href=http%3A%2F%2Fkwejk.pl%2Fobrazek%2F1952891&layout=button_count&locale=pl_PL&node_type=link&sdk=joey&show_faces=false&width=130
Outputs are the same and works identically both on response and facebook feed.
Conclusion
This is solution for my problem directly, if you are not intrested in you may do not read this paragraph
My goal was to implement (fast and simple) facebook like and like box for my website which is highly based on user created content. In the scenario from this answer I ve only to fetch proper url to 'like' in iframe tag, and facebook script will get all data from og: which can be reached within href= parameter. Only disadvantage may be lack of analytics, but these likes are only for user purposes, because I will create Facebook Page for my site, where I will post random user content - from this point I will use insight analytics.
I ve both implemented social content on site and basic statistics about my content on social site. Also if only I will want in future remake it to app with SDK etc. It is still achievable and I wont lose any performance or data from this purpose.
Btw. Thats a pity Webmasters dont ve many experts in Facebook developing, or at least are not very keen on to share their knowledge :<
